. "Furthermore, the addition of some carbide-forming elements other than vanadium can potentially increase the hardness of the coating layer up to 4,000 HV.Steels such as A2, D2, S7, and other air-hardened tool steels with hardening temperatures in the 1,650- to 1,900- degree-F range will obtain a high hardness when the tools are pulled out from the coating bath into the air." . . .